The present invention relates to a road repair and surfacing vehicle of the type which transports road repair and surfacing material to a site to be repaired or surfaced and applies the material to effect the repair or surfacing.
Devices are known for repairing holes in streets and highways commonly known as "potholes". Absent a complete repaving of the street or highway, these potholes are "patched" by filling the pothole with a combination of aggregate material such as gravel and a bitumen, where the bitumen is an asphalt or an asphalt emulsion. Devices for making such repairs are known and generally include a portable vehicle, generally self propelled, which carries a hopper containing aggregate material that has been premixed with a bitumen binder such asphalt or an emulsified asphalt binder. The premixed material is conveyed from the hopper by a screw conveyor to the location for application to the pothole.
In such devices, the premixing of the aggregate and binder material requires that the combined material be heated in order to maintain a sufficient state of fluidity for application to the pothole. However, such heating is not readily accomplished and requires an extensive application of heat to maintain a sufficient fluidity of the material during transport from the hopper to the site of its application. Additionally, the application of the premixed material is difficult due to its tendency to lump together before application to the pothole.
In applicant's U.S. Pat. No. 4,511,284, issued Apr. 16, 1985, applicant disclosed an improved repair vehicle in which cold aggregate material was imparted a swirling motion as it passed down a material discharge chute and then was sprayed with a binding material such as hot asphalt or a cold emulsified asphalt. Because the material is swirling and tumbling, the asphalt binder has a tendency to completely coat the aggregate material and, when a fast setting binder is used, the coated aggregate material binds together immediately as it fills the pothole or forms the roadway surface. Thus there is a great advantage over the prior art in that the aggregate material does not have to be premixed with the binder material and then maintained at a high temperature in order to keep a sufficient state of fluidity for application to the roadbed.
However, while the device disclosed in U.S. Pat. No. 4,511,284 functions effectively as set forth therein, it requires a great deal of power to generate sufficient air pressure to cause the aggregate material to swirl or tumble so that when the binder material is sprayed thereon, it coats the entire surface of each particle of aggregate material.
The present invention overcomes the difficulties of the prior art by providing a movable road repair and surfacing vehicle which again utilizes a cold aggregate material and an asphalt binder which can be sprayed on the aggregate material as it is deposited on the roadway surface. However, in the present invention a hollow shaft is rotatably mounted within the aggregate discharge chute and has near the bottom thereof, a projection in the form of a truncated cone attached symmetrically about the outer periphery of the rotating hollow tube adjacent to but above the lower end of the rotating tube with the large flared end of the cone downwardly and flaring outwardly and having a plurality of raised projections on the outer surface thereof for striking aggregate particles falling through the aggregate discharge chute and imparting to them a swirling outwardly flaring motion. In order to cause better adherence of the asphalt binding material to the aggregate particles, a spray of water mist is applied to the swirling aggregate particles from both above and below and then the hot asphalt binding material is sprayed thereon. The water that is sprayed from below the swirling aggregate particles is obtained from the hollow shaft rotatably mounted within the aggregate discharge chute. In addition, the asphalt binding material passes through a hollow ring surrounding and adjacent the lower end of the discharge chute to spray the tumbling, swirling particles as they are impacted by the truncated cone projection attached to the lower end of the rotating hollow shaft. In addition, a second hopper is utilized on the vehicle to carry any additive such as flyash, cement or the like, which is to be mixed with the dry aggregate in the first hopper. This will allow the use of cement to patch potholes in concrete or form a concrete roadbed. By utilizing a device of the proper size and construction, an entire roadway surface can be deposited as well as potholes patched.
Thus it is an object of the present invention to provide a road surfacing and repair vehicle having an aggregate material discharge chute in which is placed a hollow rotating tube which has on the lower end thereof a truncated cone with projections thereon to mechanically impart a swirling motion to the aggregate material leaving the discharge chute.
It is also an object of the present invention to spray a water mist on the swirling aggregate from above before applying the asphalt to cause better binding of the asphalt to the aggregate material by virtue of the capillary action of the water.
It is another object of the present invention to spray a water mist on the swirling aggregate material from below the falling material before applying the asphalt to obtain complete coverage of the aggregate with the water mist.
It is still another object of the present invention to provide a second hopper for additives or agents which are to be premixed with the aggregate material.
It is yet a further object of the present invention to provide a premixing device in the hollow discharge chute for premixing the aggregate material and any additive from the second hopper.
It is yet another object of the present invention to use a hollow ring surrounding the lower end of the aggregate material discharge chute to distribute asphalt on and coat the swirling aggregate particles.
It is still another object of the present invention to spray a water mist on top of the aggregate material by means of a hollow ring interposed between the asphalt binder hollow ring and the aggregate material discharge chute.
It is also an object of the present invention to spray a water mist on the aggregate material from below the falling material through a nozzle on the lower end of the rotating hollow tube in the center of the aggregate material discharge tube with water supplied through the rotating hollow tube.